Fad Diets and Your Digestive Health

Many studies have found that if you lose more than two pounds a week, you are setting yourself up for failure. "I realize a lot of people are successful at losing more than that a week and keeping it off, but I can tell you that the healthiest way to lose—and maintain weight—is to lose no more than a pound a week," says Frank P. Troiano, MD, Indianapolis Gastroenterology and Hepatology, and Clinical Assistant Professor at Indiana University School of Medicine.

Troiano recommends not dieting. Instead, follow a few simple food rules: avoid eating fast foods, reduce portion sizes, don't deny yourself anything (i.e., dessert, whole food groups), and be mindful of what you eat and how it makes you feel. Taking stock of how you feel after you eat foods with extremely high sugar or fat contents will help you learn to eat more intelligently. Plus, you'll focus more on the process (how you feel) instead of the scale (how much you've lost).

If you're still fixed on a fad diet, know that beyond the boredom of restriction and repetition, there may be side effects. Here's how a few popular diets may affect your digestive health.

The Diet: High-Protein
The Digestive Distress: Constipation

The emphasis of high protein is at the expense of high fiber. This may cause your digestive system to slow down, resulting in constipation.

"People start a high-protein diet because they hear it's great for weight-loss and then they start getting bloating and constipation," says Carolyn Dean, MD, ND, author of IBS for Dummies (Wiley Publishing, Inc.) and the medical director for the Nutritional Magnesium Association. "The food is heavier so it's more filling, but it lacks fiber. And fiberless food is a large percent of what you're eating."

Dr. Dean also explains another problem: the body uses a lot of gastric acid to digest protein. "People feel bloated and full after a meal because the stomach keeps trying to process the food—the food just builds up and doesn't pass along until it's broken down. It overloads the stomach's capacity to break the protein down with possibly unavailable gastric acid. In fact, people think they may have heartburn and GERD and acidity, when in fact most people have a lack of this acid that throws their digestion system off track."

She also cautions that protein requires magnesium for digestion. The higher the protein diet, the higher the magnesium you need. If you don't have enough magnesium, or overutilize the magnesium you do have, then you may experience magnesium deficiency symptoms such as low daytime energy, charley horses, heart palpitations, and muscle twitches. Also, if you have a tendency towards constipation, Dean says magnesium is a gentle muscle relaxant, so taking a supplement may help bowel movements normalize.

The Diet: Gluten-Free
The Digestive Distress: Constipation if fiber consumption is reduced

By eliminating whole grain breads, wheat, and barley, you're reducing a common source of fiber in the diet. So if you follow a gluten-free diet, you need to be sure you're consuming enough fiber from other sources: fruits, vegetables, beans, legumes, and nuts to name a few.

A lot of people go gluten free, but not necessarily for weight loss. "One reason: There's an upward trend in the gluten-free lifestyle because it makes people feel better," says Troiano. "Not all diets are going to have negative effects on the digestive system."

People may feel they're less bloated and have less gas when exposed to reduced amounts of carbohydrates that contain the gluten protein.

However, he cautions avoiding gluten will improve symptoms, but not necessarily improve overall digestion.

The Diet: Vegetarian
The Digestive Distress: Bloating, gas, and discomfort from too much fiber

Vegetarians may experience digestive side effects from eating too much fiber. "Vegetarians and vegans may find they have a lot of gas because they eat a lot of fiber, and they tend to have loose stools," says Troiano.

What's more, vegans need to be very careful about iron and B12. You may have to supplement (he advises having your doctor check your levels first). "You may [be] at risk for becoming anemic and deficient in B12. That can lead to nerve disease." In addition, he says vegetarian athletes may experience poor muscle endurance.

The Diet: Meal Replacement Drinks
The Digestive Distress: Constipation or diarrhea from lack of fiber

Though benefits include vitamins and minerals, along with adequate protein, these shakes may skimp on fiber. 

"I'm a proponent of protein shakes for breakfast. Otherwise, most people won't even eat in the morning," says Dean. However, she advises adding a green powder (fruits and veggies for fiber) to a protein shake or choosing a drink with fat, protein, and carbs to make it a meal.

You've got to be careful that you don't abuse a good thing, adds Troiano. In addition to shakes, products like Cliff bars, Balance bars, Hammer Nutrition, etc., have a role in a busy life: They prevent you from relying on junk food. "You can grab one on your way to work—they're great for the medical student in between rounds, the busy mom driving kids to different practices, the athlete training after work. But, they're not sustainable. You can overdo it. Used sparingly, and at the right time, they're fine. They have been scientifically formulated and some of them are very, very good."

The Diet: The Master Cleanse
The Digestive Distress: Loose stools, frequent diarrhea

The gist of this celebrity trend? Drinking water with lemon juice to purify and detox the system. It's purported to cleanse the digestive system.

"I like the master cleanse—for a day or so," says Dean. "People are so stressed and so toxic, so I wouldn't recommend it as a blanket diet...some people may not be able to handle it."

What she likes about it? If you experience digestive symptoms, it can sometimes be a good idea to rest the system. But instead of doing a full-fledged detox, she suggests starting with a morning or two a week, and simply drinking water with lemon. That helps cut acidity, and helps with the nausea feeling. Then you can get into the idea of doing the Master Cleanse for a whole day. 

Detox diets are controversial, and for good reason. Troiano explains: "We're talking about cleansing/purging the colon. What you have to understand is...most of the species in the colon haven't even been identified. We don't even know what's there. But what we're realizing is that if you don't have certain bugs in your system, you get a lot sicker." Without good bacteria in your gut, you increase your risk of high levels of dangerous pathogens, such as C. Diff."

"I think the Cleanse should only treat severe constipation," says Troiano. In terms of nutrition, he suggests you lose the junk food and focus on more healthful fare in order to "detox". "If you eat a healthy, balanced diet, you will most likely have [a healthier] bowel function. Eat a banana, a couple bites of fig[s], some spinach, some broccoli. Add a small piece of meat, some bread, a glass of wine—you're going to have good bowel function."




Frank P. Troiano, MD, Indianapolis Gastroenterology and Hepatology and Clinical Assistant Professor at Indiana University School of Medicine.

Carolyn Dean, MD, ND, author of IBS for Dummies (Wiley Publishing, Inc.) and the medical director for the Nutritional Magnesium Association.